It is common knowledge that self-expanding endoprostheses, of the kind described for example in U.S. Pat. No. 4,655,771, are used to treat vascular disorders. In this case, for example, an endoprosthesis arranged in the lumen at the distal end of a long catheter, which can be introduced into the (blood) vessel to be treated, is released by the catheter at a predetermined position in the vessel.
EP 0 607 468 B1 describes a long catheter for implanting a self-expanding endoprosthesis (stent) in a vessel, said catheter comprising a flexible outer catheter, a flexible inner catheter arranged therein, and a catheter tip connected via an intermediate element with the distal end of the inner catheter to form a loading chamber for the endoprosthesis. In this catheter, while the outer catheter is partially retracted, the endoprosthesis is manually reduced in diameter and introduced into or placed in the loading chamber provided, and the outer catheter is then gradually advanced over the endoprosthesis up to the tip of the catheter.
In addition, WO-A 96/93077 describes a measuring device having the form of a catheter and comprising a sleeve body, a hollow cylindrical piston rod arranged coaxially therein and possessing on its outer periphery a measuring scale, a self-expanding endoprosthesis attached to the distal end of the piston rod and capable of being drawn into the cylindrical inner space of the sleeve body, as well as an inner catheter passing axially through the piston rod, said catheter having a catheter tip at its distal end. Using this device, in a first phase the catheter is introduced into a vessel, while being monitored by X-ray means, in order to determine the length of the endoprosthesis, which is difficult to estimate from outside the body, and the required length of the endoprosthesis is then read off from the measuring scale on the piston rod. Next, the piston rod, with the endoprosthesis attached thereto, is retracted into the sleeve body of the catheter and the device is fully removed from the vessel. In a second phase, an endoprosthesis is cut to the measured length, either the endoprosthesis attached to the piston rod may be cut according to the measurement or another endoprosthesis is cut to length. The endoprosthesis of suitable length must then, however, be reintroduced (loaded) by hand into an insertion catheter, of the kind described for example, in the EP 0 607 568 B1, and it is then implanted by means of this catheter.
In an alternative embodiment, in order to simplify the loading process, the catheter is disassembled in the second phase and the endoprosthesis is drawn forwards through the sleeve body from the proximal end, using the piston rod, until a point marked on the endoprosthesis according to the measurement process projects from the distal opening of the sleeve body. The endoprosthesis is cut off at this point so that the sleeve body is loaded with a section of endoprosthesis of the required length, while the piston rod with the attached remainder of the endoprosthesis is no longer needed. Finally, in order to introduce the endoprosthesis, the catheter is reassembled with the replacement piston rod and the inner catheter.
The purpose of the invention is to create a device by means of which it is possible for an endoprosthesis of preferably predetermined dimensions, which is intended to be implanted in a vessel, to be introduced as rapidly as possible into the distal end of a catheter while maintaining safe and sterile handling conditions.